May 07, 2012

Horse domestication mystery solved (?)

I will add the abstract of the paper later when it is "live" on the PNAS site. For the moment, a link to the press release:

New research indicates that domestic horses originated in the steppes of modern-day Ukraine, southwest Russia and west Kazakhstan, mixing with local wild stocks as they spread throughout Europe and Asia. The research was published today, 07 May, in the journal PNAS.

For several decades scientists puzzled over the origin of domesticated horses. Based on archaeological evidence, it had long been thought that horse domestication originated in the western part of the Eurasian Steppe (Ukraine, southwest Russia and west Kazakhstan); however, a single origin in a geographically restricted area appeared at odds with the large number of female lineages in the domestic horse gene pool, commonly thought to reflect multiple domestication "events" across a wide geographic area.

In order to solve the perplexing history of the domestic horse, scientists from the University of Cambridge used a genetic database of more than 300 horses sampled from across the Eurasian Steppe to run a number of different modelling scenarios.

Their research shows that the extinct wild ancestor of domestic horses, Equus ferus, expanded out of East Asia approximately 160,000 years ago. They were also able to demonstrate that Equus ferus was domesticated in the western Eurasian Steppe, and that herds were repeatedly restocked with wild horses as they spread across Eurasia.

ScienceNOW also covers the new research, and reports on a contrasting viewpoint:

Not all researchers are convinced, however. Archaeologist Marsha Levine of the University of Cambridge thinks using modern genetic samples to retrace horses' evolution is a dead end. "There's been mixing of cultures and mixing of horses in this region for many thousands of years," she says. "And so when you're looking at any modern horse, you just don't know where it's from."

Bringing together many kinds of evidence is what will ultimately answer the whens and wheres of horse domestication, Levine says. "What we need to be doing is using material from excavations, sequencing ancient genes, and combining that with what we know from archaeological evidence about how animals were used in the past."

I agree with the idea that ancient DNA will ultimately confirm/reject the model presented in the paper. Of course, it may be the case that the west Eurasian steppe was the place where horse domestication happened, but it is also the place where local horses may be descended from European, West Asian, and Central Asian breeds. I'll have to read the paper to see how the problem of possible admixture between western and eastern horse breeds on the steppe is accounted for in the paper.

PNAS doi: 10.1073/pnas.1111122109

Reconstructing the origin and spread of horse domestication in the Eurasian steppe

Vera Warmuth et al.

Despite decades of research across multiple disciplines, the early history of horse domestication remains poorly understood. On the basis of current evidence from archaeology, mitochondrial DNA, and Y-chromosomal sequencing, a number of different domestication scenarios have been proposed, ranging from the spread of domestic horses out of a restricted primary area of domestication to the domestication of numerous distinct wild horse populations. In this paper, we reconstruct both the population genetic structure of the extinct wild progenitor of domestic horses, Equus ferus, and the origin and spread of horse domestication in the Eurasian steppes by fitting a spatially explicit stepping-stone model to genotype data from >300 horses sampled across northern Eurasia. We find strong evidence for an expansion of E. ferus out of eastern Eurasia about 160 kya, likely reflecting the colonization of Eurasia by this species. Our best-fitting scenario further suggests that horse domestication originated in the western part of the Eurasian steppe and that domestic herds were repeatedly restocked with local wild horses as they spread out of this area. By showing that horse domestication was initiated in the western Eurasian steppe and that the spread of domestic herds across Eurasia involved extensive introgression from the wild, the scenario of horse domestication proposed here unites evidence from archaeology, mitochondrial DNA, and Y-chromosomal DNA.

26 comments:

Its a very interesting paper, more than the previous!, but Dienekes tell me which horse represents the Rikvedic horse with unusual 34 ribs as clearly mentioned here: http://www.sacred-texts.com/hin/rigveda/rv01162.htmdo you think there is any arabian connection?

"New research indicates that domestic horses originated in the steppes of modern-day Ukraine, southwest Russia and west Kazakhstan, mixing with local wild stocks as they spread throughout Europe and Asia".

Hasn't that always been the most likely scenario? It has certainly been my preferred scenarion for many years.

"Based on archaeological evidence, it had long been thought that horse domestication originated in the western part of the Eurasian Steppe (Ukraine, southwest Russia and west Kazakhstan)"

Exactly.

"Archaeologist Marsha Levine of the University of Cambridge thinks using modern genetic samples to retrace horses' evolution is a dead end. 'There's been mixing of cultures and mixing of horses in this region for many thousands of years,' she says. 'And so when you're looking at any modern horse, you just don't know where it's from.'"

Surely it makes sense that once someone had learned to do domesticate horses domestication would have spread, and, as it spread, locals would have supplimented their herds with locally captured horses.

behl et al (2007) studied DNA of five Indian caballus horse breeds viz. Marwari, Spiti, Bhutia, Manipuri, Zanskari and the European thoroughbred horse. The results showed that the genetic distance varied as the geographical distance between the lineages. Their is a geographical structuring of the horse breeds in India. This means the breeds under question, have evolved from their present location over a very long period of time, and have not been imported from ouside of India.

It would be very interesting to compare the genetics of the spread of horse domestication from the steppes, with the spread of Indo-european languages, and the associated human genetics within the same time period and geographies. Domesticated horses could have been the "killer app" that gave steppe warriors the deciding advantage over other cultures.

Perhaps somebody has already pursued this type of comparative research of horse vs human DNA mapping. An recent example of comparative DNA studies of two species was a recent paper that used the genetics of human lice to arrive at some conclusions regarding the development of early hominid species.

lol. Depends on which side of the arugment your one, A person from India will consider your approach western centric Abrahamic ideological approach. To support the ancestoral ideology of jews, christians and muslims of the middle east. Genetics itself refutes any Invasion theory, its not hinduvta, Nazi, Western imperialistic its TRUTH.

To Nathan, why should Indians, and India accept a European Abrahamic centric notion of Aryan invasion theory of the 18th century. Such claims should never be accepted without proof. To be honest the Indian case for Arya migration out of India hold more weight and evidence than a proposed Aryan Migration into India. You would have to be a fool to dismiss Abrahamic centric ideology of the past 1000years as meaningless, Islam and Christianity are adherents of Aryan Invasion because it simply backs Noahs three son lineage of the world. Hinduvta has more merit than Abrahamic centric ideology, i have read more than enough history to see the gaps and distortions.

The fact that you phrase Western Indoloy scholarship as Abrahamic centric says a lot about you and your right wing Hindu bias. Western Indologists do not subscribe to some centuries old Abrahmaic notion of races. This is a canard that Hindutva has been putting out there.

OIT has no merit whatsever, no peer reviewed journals or reputable academic publications support the nonsense. It is as bunk as the nonsense Arthur Kemp peddles.

I am South Asian and I choose to believe in Western scholarship over ethno-nationalist revisionism peddled by Hindutva.

If horses were domesticated in the Ukraine, why is it that the same area that domesticated donkeys, sheep, goats, and taurine bovids has the highest genetic diversity of horse varieties? Surely that is a strong indicator of possible domestication in the southern Caucasus/NW Iran/east Anatolia.

"They were also able to demonstrate that Equus ferus was domesticated in the western Eurasian Steppe, and that herds were repeatedly restocked with wild horses as they spread across Eurasia".

This is a classic example of what one of my friends has called 'the wave theory of evolution'. Evolution proceeds throught he expansion of genetic waves through species. In this case the vector of an expanding idea of horse domestication carried genes (including mt-DNA and Y-DNA) in an expanding wave from the western Eurasian Steppe. It is quite possible that all evolution proceeds in the same manner. We don't find some suddenly 'superior' small group of individuals expanding at the expense of all their close relations.

"The results showed that the genetic distance varied as the geographical distance between the lineages. Their is a geographical structuring of the horse breeds in India".

A cline is what we would expect with an expanding genetic wave. The further we move from the source the less of the original genetic combination we would find.

"It would be very interesting to compare the genetics of the spread of horse domestication from the steppes, with the spread of Indo-european languages, and the associated human genetics within the same time period and geographies".

Closely connected would be my guess. And other human expansions, especially of mt-DNA and Y-DNA, would most likely have been driven by other improvements in technology. That is what has led to the surprising lack of diversity of human haplogroups as compared to those of other species.

"Were there not two breeding developments: an early selection for small draft (riderless) horses, and a later selection for large horses that could be ridden?"

The old idea (as far as I know no contrary evidence) is that horses were first domesticated for meat, then draft, and only much later for riding.

Domesticated horses could have been the "killer app" that gave steppe warriors the deciding advantage over other cultures.

Before people are getting carried away, I just want to put a few facts, out here:

* Outside the steppes, horses are expensive to maintain (need high-protein food competing with humans, and stashes of that in areas with long winters and snow cover) and offer no transportation benefit until roads are built (i.e., in late classical or medieval times, in much of north/central Europe).

* For this reason, apart from a very few examples of status symbol or reverence, horses are almost absent in the archaeological record of Germany and Western Poland until the late bronze/ iron age in the South, and until Roman times and later in the North.

* There were most likely 2,000 to 3,000+ years of IE languages in the above regions before horses became important.

"Just because you don't like historical facts does not make it chauvinism."

Puzzling comment, as I never said which "facts" I did not "like." Just because research is "Western" does not make it better or worse. I would also bet that quite a few of these "Western" researchers would be mortified at being described as part of an old-fashioned construct.

Nathan if you think that this aryan theory is not based on the three son linage of Noah which has been present in Christianity, Islam and Judaism, for the past 1000years, as a ideological that has shaped belief itself. Aryan theory has been disproved BEYOND doubt. You are south Asian, i dont know you, But i already know your christian and you might like to DILUTE or DELINK the christian element in aryan theory but i can see it CLEAR as day. Christian, and muslims call them Hinduvta, and Hinduvta call them Imperialistic. The difference being, Hinduvta has never colonized and occupied another territory, and therefore the legacy of occupation, deceit, corruption, enslavement, doesnt exist as it does in the Christian world.

Nathan, your whole notion of Aryan invasion is based on the following format, Dravidain from Elam, sons of ham, where great cultivators, they got pushed down by white tribes of shem and japeth, who attacked the natives of india, and then the white aryan created a caste system and placed it onto of the natives, and put themselves at the highest position. You see this story is needed to give support to Noahs three son lineage of the world. Therefore if India was the home of european and central asian civilisation it completely undermines the Faith of three religions, Jews, Christians and Muslims to such a degree that it would prove fatal to its beleif system. Muslims, chrisitans and jews ALL are adherents of the Aryan invasion, its more a religious ideology than a reality. The colonization of south americam, north america, africa, india, china, was PRIMIARLY done to religious sanctions to conquer in the name of christ, muslims did in the name of Allah. The very concept of Aryan invasion is laced with racist connotations, white skinned tribes invaded and civilised, which is an exact mirror of the Biblical version of Noah, that the tribes of light skinned Arabs and Europeans civilised the world. Its a nice story, but as Dienekes knows the evidence of Aryan invasion is SO weak, that it has not been proved at all, and in fact the evidence always suggest migration from India. You wont every be able to show one set of data that proves migration into india from central asisa or europe.

formerjersey boy"Puzzling comment, as I never said which "facts" I did not "like." Just because research is "Western" does not make it better or worse. I would also bet that quite a few of these "Western" researchers would be mortified at being described as part of an old-fashioned construct. "

I made the following comment in my first reply to bmdriver: "Western academia does not accept horse domestication in South Asia as the evidence does not support it."

To which you responded by quoting the above comment and stating: " We should not exchange one chauvinism for another one. "

You are insinuating that both positions (Hindutva's and Western Academia's ) on South Asian horse domestication are chauvinistic.

As for the rest of your post, I don't know what you are referring to when you say Western researches would be mortified.

Possible evidences do exist, even if there is nothing totally clear, you just do your best to ignore it.

And stop mumbling about religious bias. A lot of western scientists are agnostic or atheists.

"It would be very interesting to compare the genetics of the spread of horse domestication from the steppes, with the spread of Indo-european languages - Closely connected would be my guess"

Sounds reasonable at least. For the most western IE language (old Irish ech) and the most eastern one (Tocharian A yakwe (pretty close to PIE ekw- (-os), Just like archaic latin equos (i.e. ekw- (-os))) to share the same stem for this animal, it's definitely a possibility. It doesn't look like a late loanword in all these languages since these words have generally apparently fully undergone the same typical changes since the PIE stage than the other words in their language (starting with old Indic asva and old Iranic aspa).

Thanx to wagg for bring this line of discussion back to a serious discussion of the facts, and away from "scientific" conclusions actually based on religious convictions. I personally think more future researchers will end up concluding that India was the most likely region of origin of the R1a Y DNA haplotype, but inserting this data into a religious paradigm does NOT help any serious scientific discussions.

I just read through a paper from Klyosov & Rozhanski, their conclusion is that R1a first appeared in the Altay/Central Asia area 20K YBP, who started migrating southward and westward, and a portion ended up in South Asia 12K YBP. A second wave of R1a, this one closer to the type existing on the Russian plains, came into South Asia in the 2nd millenium BC. The authors also state that R1b bearers in Europe were not likely Indo-european to begin with, even though they mostly now speak Indo-european languages.

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